Modules and Coroutines

Modules

export module math;

export int add(int a, int b) {
    return a + b;
}

import math;

• Use modules to reduce header duplication and improve build boundaries.
• Treat toolchain support as the deciding factor for adoption speed.

Coroutines

generator<int> countdown(int from) {
    while (from > 0) {
        co_yield from--;
    }
}

• co_return finishes with a value.
• co_yield produces a sequence element.
• co_await suspends until another awaitable is ready.

Adoption guidance

• Add modules first in leaf libraries or new components.
• Add coroutines through a real abstraction such as a task type or generator library, not as raw promise-type experiments in production code.

Reality check

• Modules are a build-system and toolchain feature as much as a language feature.
• Coroutines are usually not useful by themselves; they become useful with a task, generator, or async I/O abstraction.